1. Field of the Invention
The present invention relates to a spherical bearing, in particular, a torque adjusting mechanism in which a sliding torque of a spherical bearing is adjusted on an inner circumference of an outer race by regulating a pressing force against a spherical surface of the inner race.
2. Conventional Art
In general, in a spherical bearing, as shown in FIGS. 10, 11, an inner race 51 formed with a spherical surface 51a is supported rotatably and slidably by an outer race 52 on the inner circumference 52a which is covered with a sliding liner 53, and the outer race 52 is retained into a race retention hole 55 formed on a housing 54 and installed in the housing 54 by making end faces 52b of the outer race 52 engaged with a pair of snap rings 57 retained in annular grooves 56 provided at a given spacing on the inner wall surface 55a of the race retention hole 55.
In such a spherical bearing, the sliding torque was adjusted by regulating the fitting state between the inner wall surface 55a of the race fitting hole 55 and periphery surface 52c of the outer race 52 and changing a contact surface pressure between the inner circumference 52a of the outer race 52 and the spherical surface 51a of the inner race 51. Further, it has been practiced that, by forming, in an assembly of the outer race 52 and the inner race 51, in advance, the sliding torque between the outer race 52 and the inner race 51 to be larger and releasing a remaining stress of the outer race 52 by a specific releasing machine (not shown) to regulate the contact surface pressure between the inner circumference surface 52a and the spherical 51a of the inner race 51 and to regulate the sliding torque of the assembly to a desired value.
However, in the conventional spherical bearing torque adjusting mechanism by fitting the inner wall surface 55a of the race retention hole 55 and the periphery surface 52c of the outer race 52, since the working precision of the race retention hole 55 and outer race 52 becomes varied, the contact surface pressure between the inner circumference surface 52a of the outer race 52 and the spherical surface 51a of the inner race 51 does not become constant, so that it is difficult to obtain a stable sliding torque. Further, the following problems have been brought out; in the torque adjusting mechanism of the spherical bearing to adjust the sliding torque by releasing the residual stress of the outer race 52 with a specific releasing machine, although a given sliding torque can be obtained, an exclusive releasing machine becomes necessary, and since the number of process due to the releasing machine is increased, costs increase greatly, and further an extra space for a releasing machine becomes necessary in a factory. In addition, once releasing the sliding torque with the releasing machine, it is impossible to make the sliding torque recovered, in addition, if the sliding torque is too much released, an expensive assembly has been wasted. Further, even in a spherical bearing, the sliding torque is appropriately adjusted, due to wearing of the sliding liner 53, the sliding torque is reduced, and in order to obtain an initial sliding torque, an expensive assembly has to be replaced.
Accordingly, the present invention has been made in the light of the above problems and it is the object of the present invention to provide a torque adjusting mechanism of the spherical sliding bearing, in which a constant sliding torque is easily obtained, and even if the sliding torque is reduced due to the wearing of the sliding liner, by re-adjusting, the sliding torque can be restored.
In order to attain the above object, according to a first aspect of the present invention, in a sliding torque adjusting mechanism of a spherical sliding bearing which is formed by fitting a spherical bearing made of an outer race and an inner race supported rotatably on the inner race circumference of the outer race with a race retention hole, into which the spherical bearing is retained, a screw portion is provided on one side of the inner wall of the race fitting hole with a given depth coaxially with the race retention hole, and on the other side of the race retention hole an annular groove to be fit with a first snap ring is formed, further, on one end of the periphery of the outer race, an outer conical surface of a given tapered angle is provided and a stopping screw engaged with the screw portion, which has a through hole in the axial direction, and on one end of the through hole, an inner conical surface which is fit with the outer conical surface is provided.
By thus constructed, while the stopping screw being engaged with the screw portion formed on one inner wall surface of the race retention hole, and by tightening the stopping screw with the inner surface of the inner conical surface of the periphery of the outer conical surface is pressed, so that a contact surface pressure between the inner surface of the outer race and the spherical surface of the inner race is regulated by regulating the tightening force of the stopping screw, as a result, the sliding torque of the spherical bearing can be adjusted.
Further, according to a second aspect of the present invention, on the inner wall of the through hole of the stopping screw, an annular groove is formed with which a second snap ring is retained.
By thus constructed, due to the tension of the second snap ring, the contact surface pressure between the stopping screw and the screw portion of the race retention hole can be increased to prevent the stopping screw from being loosened.